The present invention is related to prosthetic heart valve replacement, and more particularly to devices, systems, and methods for transcatheter delivery of collapsible prosthetic heart valves.
Prosthetic heart valves that are collapsible to a relatively small circumferential size can be delivered into a patient less invasively than valves that are not collapsible. For example, a collapsible valve may be delivered into a patient via a tube-like delivery apparatus such as a catheter, a trocar, a laparoscopic instrument, or the like. This collapsibility can avoid the need for a more invasive procedure such as full open-chest, open-heart surgery.
Collapsible prosthetic heart valves typically take the form of a valve structure mounted on a stent. There are two types of stents on which collapsible valves are mounted: a self-expanding stent and a balloon-expandable stent. To place a collapsible valve into a delivery apparatus and ultimately into a patient, the valve must first be collapsed or crimped to reduce its circumferential size.
When a collapsed valve has reached the desired implant site in the patient (e.g., at or near the annulus of the patient's heart valve that is to be replaced by the prosthetic valve), the prosthetic valve can be released from the delivery apparatus and re-expanded to full operating size.
Despite the various improvements that have been made to the collapsible prosthetic heart valve delivery process, conventional delivery devices, systems, and methods suffer from some shortcomings. For example, the self-expanding collapsible valve may be held in a catheter by stent retention members that are inserted into the retainer portion of the catheter. During deployment of the self-expanding valve into the desired area (e.g., the aortic valve annulus), the high frictional force produced during unsheathing of the valve may cause high axial forces to be applied directly to the two or three retention members, which may damage or deform the stent struts that support the retention members.
Furthermore, the delivery process may cause the stent to become twisted relative to the retainer portion of the catheter, which may make it difficult to release the valve because the stent retention members may catch on the retainer during deployment.
There therefore is a need for further improvements to the devices, systems, and methods for transcatheter delivery of collapsible prosthetic heart valves. Among other advantages, the present invention may address one or more of these shortcomings.